ABSTRACT Given the chronic and pervasive impairments associated with Attention Deficit Hyperactivity Disorder (ADHD), high rates of child comorbidity, and heightened problems in child social interactions and relationships (Lahey & Waldman, 2003), children with ADHD are at risk for poor outcomes and require intensive interventions, which are then periodically followed by brief interventions to ensure that treatment progress is maintained. Despite substantial success in clinical interventions, long-term adherence can be challenging. Moreover, as children with ADHD become adolescents, it is common for them to receive less frequent treatment and support for their disorder in spite of the fact that they face increasingly difficult situations in academic (demands of a high school curriculum) and social (exposure to drugs, alcohol) settings. Research has shown that self-regulation is a robust predictor of positive outcomes in adulthood and that early adolescence is a critical period for promoting self-regulation in order to prevent life-altering mistakes, which often have their roots in the high school years (Moffit et al., 2011). Our multidisciplinary research team has extensive experience developing ADHD and technological interventions. Here we propose to develop and pilot a novel technology called CoolCraig, a wearable and connected system that combines a fitness tracker, mobile phone app, and web portal, which can be used to deliver intervention, promote self-regulation, and improve adherence to treatment over time for adolescents with ADHD. Our first aim is to establish key design principles for the support of adolescents with ADHD and implement these principles in the CoolCraig system. We will conduct a series of design workshops with 24 participants (adolescents, parents, clinicians) to build on our preliminary research and develop a wearable, context-aware system for supporting long-term cognitive behavioral change. Our second aim is to evaluate the feasibility and acceptability of CoolCraig. To address this aim, we will recruit 20 adolescents (ages 12-15) with ADHD; participants will use CoolCraig for 16 weeks to reinforce, extend, and maintain treatment gains. To gather preliminary data for a future clinical trial, we will also collect outcomes data to assess the impact of CoolCraig on self-regulation, health behaviors, and ADHD symptoms, and we will interview participants' parents (or caregivers) and clinicians. In addition, CoolCraig will use wearable and smartphone sensors to record a variety of self-report and automatic physiological and context data. These data, combined with self-reports gathered through the system, will provide the preliminary data needed to develop an intelligent system to identify, predict, and intervene to promote more healthy behaviors.